Nasco Whirl-Pak® Sterile Thio-Bags® are specially designed for sampling chlorinated water. This single use, sterilized, lightweight, unbreakable container is always ready for immediate use. Used by many states and EPA approved, this strong transparent bag holds a nontoxic, nonnutritive tablet containing 10 mg of active sodium thiosulfate to neutralize chlorine at the time of collection. As an added feature, Thio-Bags® have a Convenient Write-On Strip and markings for 100 ml and 300 ml measurements. Bags are made of high-quality blended polyethylene.